Cylinder head gasket

Abstract

A cylinder-head gasket with a metal sealing layer (10) in which there are provided at least one combustion-chamber opening (B), screw holes around said opening for cylinder-head screws, and a combustion-chamber sealing bead (16) stamped into the sealing layer, wherein the combustion-chamber sealing bead has, on its convex side, a crest portion (30a′) which lies between two bead legs (32a′), by means of which bead legs the crest portion is connected to the sealing layer, and wherein the combustion-chamber sealing bead has screw portions, each of which lies closest to a screw hole, and has intermediate portions between the screw portions; in order to improve the sealing capability of the cylinder-head seal, the deformation resistance of the bead legs with respect to pressing forces is greater, at least in longitudinal regions of the intermediate portions, than in screw portions of the combustion-chamber sealing bead.

1 . A cylinder-head gasket comprising a metal sealing layer in which there are provided at least one combustion-chamber opening, screw holes each defining a screw hole axis around said opening for the passage of cylinder-head screws, and a combustion-chamber sealing bead stamped into the sealing layer, wherein the combustion-chamber sealing bead has, on its convex side, a crest portion which extends in the bead longitudinal direction and is arranged along the combustion-chamber sealing bead in a plan view of the sealing layer between two bead legs, by means of which bead legs the crest portion is connected to regions of the sealing layer bordering the combustion-chamber sealing bead, into which regions the bead legs transition in each case by a bead foot, and wherein in a plan view of the sealing layer the screw holes are arranged at a spacing from the combustion-chamber opening and at spacings from one another in the peripheral direction of the combustion-chamber opening and the combustion-chamber sealing bead runs between the combustion-chamber opening and the screw holes and has screw portions, each of which lies closest to a screw hole, and intermediate portions between these screw portions,
 wherein the deformation resistance of the bead legs with respect to pressing forces acting on the crest portion in the direction of the screw hole axes is greater at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead than in screw portions of the combustion-chamber sealing bead.   
     
     
         2 . The cylinder-head gasket in accordance with  claim 1 , wherein, in intermediate portions along the combustion-chamber sealing bead at least in longitudinal regions of the intermediate portions,
 (a) the cross-section of the bead legs in its cross-sectional shape and/or cross-sectional area   and/or   (b) the hardness or compressive strength of the metal of the bead legs, averaged over the cross-section of the bead legs,   varies such that, in these longitudinal regions of the intermediate portions, the deformation resistance of the combustion-chamber sealing bead measured in the direction of the screw hole axes differs locally along the combustion-chamber sealing bead.   
     
     
         3 . The cylinder-head gasket in accordance with  claim 1 , wherein along the combustion-chamber sealing bead in zones of the bead legs delimited by planes running parallel to the plane of the sealing layer, at least in longitudinal regions of the intermediate portions, the material thickness and/or the structure of the metal of the bead legs varies such that, along the combustion-chamber sealing bead in these longitudinal regions of the intermediate portions, the deformation resistance of the combustion-chamber sealing bead measured in the direction of the screw hole axes is different locally along the combustion-chamber sealing bead. 
     
     
         4 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the combustion-chamber sealing bead, the cross-section of said bead and/or the structure of the metal of the sealing layer varies in such a way that when the cylinder-head gasket is installed and pressed between engine components, the crest portion of the combustion-chamber sealing bead is acted on all over, in the intermediate portions of said bead, by pressing forces sufficient to provide an adequate sealing of combustion-chamber gases. 
     
     
         5 . The cylinder-head gasket in accordance with  claim 1 , wherein, at least in longitudinal regions of the intermediate portions in cross-sections through the intermediate portions, the material thickness of the bead legs and/or the structure of the metal of the bead legs varies
 (a) along these longitudinal regions of the intermediate portions   and/or   (b) at least in some of these cross-sections along the bead legs,   such that the deformation resistance of the combustion-chamber sealing bead, measured in the direction of the screw hole axes, is locally different along the combustion-chamber sealing bead, at least in these longitudinal regions of the intermediate portions.   
     
     
         6 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the combustion-chamber sealing bead, the cross-section of the combustion-chamber sealing bead and/or the structure of the metal of the sealing layer varies at least substantially in the two sealing legs. 
     
     
         7 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the combustion-chamber sealing bead at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead, the crest portion of the combustion-chamber sealing bead is provided with at least one stamped protrusion extending in the longitudinal direction of the combustion-chamber sealing bead. 
     
     
         8 . The cylinder-head gasket in accordance with  claim 7 , wherein the protrusion projects in the direction pointing away from the bead feet. 
     
     
         9 . The cylinder-head gasket in accordance with  claim 1 , wherein the combustion-chamber sealing bead, on its concave side, forms a channel extending in the bead longitudinal direction and having a channel base, and wherein, in cross-sections through the combustion-chamber sealing bead, at least the channel thereof is formed at least substantially mirror-symmetrically with respect to a line running perpendicularly to the sealing layer plane. 
     
     
         10 . The cylinder-head gasket in accordance with  claim 1 , wherein the width of the crest portion of the combustion-chamber sealing bead, measured on the convex side of the combustion-chamber sealing bead in a plan view of the sealing layer, is at least substantially constant along the combustion-chamber sealing bead. 
     
     
         11 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the entire combustion-chamber sealing bead, the height of the bead legs measured perpendicularly to the plane of the sealing layer is at least substantially constant. 
     
     
         12 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the entire combustion-chamber sealing bead, the crest portion on the convex side of the combustion-chamber sealing bead forms at least one support face, which extends along the combustion-chamber sealing bead and runs at least approximately parallel to the sealing layer plane. 
     
     
         13 . The cylinder-head gasket in accordance with  claim 1 , wherein, along the entire combustion-chamber sealing bead, the longitudinal direction of each bead leg arising in cross-sections through the combustion chamber sealing bead forms an angle with the perpendicular to the sealing layer plane, the size of which angle is at least approximately 0° or at least approximately 5° to at least approximately 45°. 
     
     
         14 . The cylinder-head gasket in accordance with one of  claim 1 , wherein, along the entire combustion-chamber sealing bead, in cross-sections therethrough, the combustion chamber sealing bead, on its convex side, forms a land portion with an outer contour, the portions of which facing away from one another form an angle with the perpendicular to the sealing layer plane, the size of which angle is at least approximately 0° to at least approximately 5° or at least approximately 10° to at least approximately 45°. 
     
     
         15 . The cylinder-head gasket in accordance with  claim 1 , wherein the combustion-chamber sealing bead, on its concave side, forms a channel extending in the bead longitudinal direction, wherein, in cross-sections through intermediate portions of the combustion-chamber sealing bead, at least through longitudinal regions of the intermediate portions, the channel has a contour with contour portions facing away from one another in relation to a perpendicular to the sealing layer plane, and wherein a tangent to each of these contour portions forms an angle with a perpendicular to the sealing layer plane, the size of which angle is at least approximately 10° to at least approximately 50° or at least approximately 20° to at least approximately 60°. 
     
     
         16 . The cylinder-head gasket in accordance with  claim 1 , wherein the metal sealing layer is a sheet steel made of a steel which, in unformed regions of the sealing layer, in particular in regions of the sealing layer directly bordering the combustion-chamber sealing bead, is more ductile, namely is more easily formable, than spring steels. 
     
     
         17 . The cylinder-head gasket in accordance with  claim 16 , wherein the steel in unformed regions of the sealing layer is a cold-formable and strain-hardenable steel. 
     
     
         18 . The cylinder-head gasket in accordance with  claim 16 , wherein the steel is strain-hardened at least in regions of the combustion-chamber sealing bead in comparison to the steel in unformed regions. 
     
     
         19 . The cylinder-head gasket in accordance with  claim 18 , wherein the steel is strain-hardened to the greatest extent at least in regions of the bead legs. 
     
     
         20 . The cylinder-head gasket in accordance with  claim 16 , wherein the properties determining the formability of the steel used for production of the sealing layer are substantially the same as the formability-determining properties of a steel having material number 1.0338. 
     
     
         21 . The cylinder-head gasket in accordance with  claim 1 , wherein the combustion-chamber sealing bead, on its concave side, forms a channel extending in the bead longitudinal direction, wherein, in cross-sections through intermediate portions of the combustion-chamber sealing bead, at least through longitudinal regions of the intermediate portions, the channel, as compared with the channel in cross-sections through screw portions of the combustion-chamber sealing bead, has an additional recess extending in the direction of the convex side of the combustion-chamber sealing bead. 
     
     
         22 . The cylinder-head gasket in accordance with  claim 21 , wherein the channel inclusive of its additional recess, in cross-sections through the combustion-chamber sealing bead, is at least substantially mirror-symmetrical with respect to a line running perpendicularly to the sealing layer plane. 
     
     
         23 . The cylinder-head gasket in accordance with  claim 21 , wherein, in cross-sections through the combustion-chamber sealing bead, the greatest width of the additional recess is smaller than the width of the channel at the transition thereof into the side of the sealing layer facing away from the convex side of the combustion-chamber sealing bead. 
     
     
         24 . The cylinder-head gasket in accordance with  claim 1 , wherein the combustion-chamber sealing bead, on its concave side, forms a channel extending in the bead longitudinal direction, stamped into the metal sealing layer, and having a channel base at its deepest point in cross-sections through the combustion-chamber sealing bead, and wherein, in cross-sections through the combustion-chamber sealing bead, the material thickness of the combustion-chamber sealing bead in the region of the channel base in intermediate portions of the combustion-chamber sealing bead is smaller, at least in longitudinal regions of the intermediate portions, than in screw portions of the combustion-chamber sealing bead. 
     
     
         25 . The cylinder-head gasket in accordance with  claim 24 , wherein, as a result of the stamping of the channel, the metal of the sealing layer in the region of the channel base is formed in first longitudinal regions of the intermediate portions of the combustion-chamber sealing bead with a forming degree Φ1, and outside these first longitudinal regions with a forming degree Φ 2 , wherein Φ 1  is greater than Φ 2 . 
     
     
         26 . The cylinder-head gasket in accordance with  claim 21 , wherein the channel has an additional recess in the first longitudinal regions of the intermediate portions. 
     
     
         27 . A cylinder-head gasket comprising a metal sealing layer, in which there are provided at least one combustion-chamber opening, screw holes each defining a screw hole axis around said opening for the passage of cylinder-head screws, and a combustion-chamber sealing bead stamped into the sealing layer, wherein in a plan view of the sealing layer the screw holes are spaced from the combustion-chamber opening and are arranged at spacings from one another in the peripheral direction of the combustion-chamber opening, and the combustion-chamber sealing bead runs between the combustion-chamber opening and the screw holes and has screw portions, each of which lies closest to a screw hole, and between the screw portions has intermediate portions, wherein the combustion-chamber sealing bead, on its concave side, forms a channel, which extends in the bead longitudinal direction, is stamped into the sealing layer, and has a channel base, and wherein, in cross-sections through the combustion-chamber sealing bead at the channel base the material thickness of the sealing layer in intermediate portions of the combustion-chamber sealing bead, specifically at least in longitudinal regions of the intermediate portions, is smaller than in screw portions of the combustion-chamber sealing bead. 
     
     
         28 . The cylinder-head gasket in accordance with  claim 27 , wherein, in cross-sections through the combustion-chamber sealing bead, the depth of the channel in intermediate portions of the combustion-chamber sealing bead, specifically at least in longitudinal regions of the intermediate portions, is greater than in screw portions of the combustion-chamber sealing bead, and wherein, in intermediate portions of the combustion-chamber sealing bead, specifically at least in longitudinal regions of the intermediate portions, the cross-sectional shape of the channel deviates from the cross-sectional shape of the channel in screw portions. 
     
     
         29 . The cylinder-head gasket in accordance with  claim 28 , wherein, in cross-sections through the combustion-chamber sealing bead, the cross-sectional area of the channel in intermediate portions, specifically at least in longitudinal regions of the intermediate portions, is greater than in screw portions. 
     
     
         30 . The cylinder-head gasket in accordance with  claim 29 , wherein, in cross-sections through the combustion-chamber sealing bead, the width of the channel decreases in the direction toward the channel base, more specifically at least in intermediate portions of the combustion-chamber sealing bead. 
     
     
         31 . The cylinder-head gasket in accordance with  claim 30 , wherein, in cross-sections through the combustion-chamber sealing bead, the degree of the decrease in the width of the channel in the direction toward the channel base in intermediate portions, specifically at least in longitudinal regions of the intermediate portions, is greater than in screw portions. 
     
     
         32 . A method for producing a cylinder-head gasket with a metal sealing layer in which there are provided at least one combustion-chamber opening, screw holes each defining a screw hole axis around said opening for the passage of cylinder-head screws, and a combustion-chamber sealing bead stamped into the sealing layer, wherein the combustion-chamber sealing bead has, on its convex side, a crest portion which extends in the bead longitudinal direction and is arranged along the combustion-chamber sealing bead in a plan view of the sealing layer between two bead legs, by means of which bead legs the crest portion is connected to regions of the sealing layer bordering the combustion-chamber sealing bead, into which regions the bead legs transition in each case by a bead foot, and wherein in a plan view of the sealing layer the screw holes are spaced from the combustion-chamber opening and are arranged at spacings from one another in the peripheral direction of the combustion-chamber opening and the combustion-chamber sealing bead runs between the combustion-chamber opening and the screw holes and has screw portions, each of which lies closest to a screw hole, and intermediate portions between the screw portions, wherein, in order to attain local increases in the deformation resistance of intermediate portions of the combustion-chamber sealing bead with respect to pressing forces acting on the crest portion of said bead in the direction of the screw hole axes when stamping intermediate portions, bead legs are produced at least in longitudinal regions of the intermediate portions, with the cross-section of said bead legs varying in its shape and/or area and/or structure
 (a) along these longitudinal regions of the intermediate portions   and/or   (b) along the bead legs in cross-sections therethrough in at least part of these cross-sections,   such that the deformation resistance of each of the bead legs, measured in the direction of the screw hole axes, is locally different along the combustion-chamber sealing bead at least in these longitudinal regions of the intermediate portions.   
     
     
         33 . The method in accordance with  claim 32 , wherein, as the combustion-chamber sealing bead is stamped into the sealing layer, a basic bead with an at least substantially constant cross-section along the basic bead and with screw portions, each arranged closest to a screw hole, and intermediate portions situated between said screw portions is firstly stamped into the sealing layer, whereupon at least longitudinal regions of these intermediate portions of the basic bead are then formed by stamping, at least such that there are produced the bead legs of the combustion-chamber sealing bead that vary in their cross-section and/or their structure. 
     
     
         34 . The method in accordance with  claim 32 , wherein, as the intermediate portions of the combustion-chamber sealing bead are stamped, at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead, the metal of the sealing layer is strain-hardened locally by yield pressure forming. 
     
     
         35 . The method in accordance with  claim 32 , wherein, along the combustion-chamber sealing bead at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead, the crest portion of said bead is provided by stamping with at least one protrusion extending in the longitudinal direction of the combustion-chamber sealing bead. 
     
     
         36 . The method in accordance with  claim 34 , wherein, as the region of the crest portion provided with the protrusion is stamped, metal of the sealing layer is displaced into the bead legs by yield pressure forming. 
     
     
         37 . A cylinder-head gasket produced by a method in accordance with  claim 32 . 
     
     
         38 . A multi-cylinder reciprocating internal combustion engine with an engine block, a cylinder head, and a cylinder-head seal, which is clamped and pressed by means of cylinder-head screws between component sealing faces of the engine block and cylinder head and has a metal sealing layer, in which there are provided a combustion-chamber opening for each cylinder of the engine, screw holes around said opening for the passage of cylinder-head screws, and a combustion-chamber sealing bead stamped into the sealing layer, wherein the combustion-chamber sealing bead on its convex side has a crest portion extending in the bead longitudinal direction, which crest portion is arranged along the combustion-chamber sealing bead, in a plan view of the sealing layer between two bead legs, by means of which bead legs the crest portion is connected to regions of the sealing layer bordering the combustion-chamber sealing bead, into which regions the bead legs transition in each case by means of a bead foot, and wherein, in a plan view of the sealing layer, the screw holes are spaced from the combustion-chamber opening and are arranged at spacings from one another in the peripheral direction of the combustion-chamber opening, and the combustion-chamber sealing bead runs between the combustion-chamber opening and the screw holes and has screw portions, each of which lies closest to a screw hole, and between the screw portions has intermediate portions, and wherein at least one of the components constituted by the engine block and cylinder head has, in its component sealing face, at least one sealing face region, in which the component rigidity of this component with respect to pressing forces directed perpendicularly to its component sealing face is lower than in sealing face regions of this component adjacent to this sealing face region, wherein the deformation resistance of the bead legs with respect to pressing forces oriented perpendicularly to the sealing layer and acting on the crest portion is greater, at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead, than in screw portions of the combustion-chamber sealing bead, and wherein, along at least one intermediate portion of the combustion-chamber sealing bead of the clamped cylinder-head seal, the deformation resistance of the bead legs is adapted at least to the locally different component rigidity of the at least one component constituted by the engine block or cylinder head in the region of its component sealing face pressed against the intermediate portion of the combustion-chamber sealing bead, in such a way that sealing face regions of lower component rigidity are associated with bead leg regions of greater deformation resistance. 
     
     
         39 . The internal combustion engine in accordance with  claim 38 , the engine block of which has, for each cylinder, a cylinder liner with a liner sealing face facing the cylinder-head seal and cooperating therewith, with a liner sealing face region surrounding the axis of the cylinder liner, against which linear sealing face region the combustion-chamber sealing bead of the cylinder-head seal is pressed, wherein the combustion-chamber sealing bead abuts with its crest portion against this liner sealing face region. 
     
     
         40 . The internal combustion engine in accordance with  claim 39 , wherein the cylinder liner has, at its outer periphery, an annular flange, by means of which the cylinder liner is supported in the direction of its axis in the engine block, and wherein, in a plan view of the cylinder-head seal, the crest portion of the combustion-chamber sealing bead lies over the flange of the cylinder liner. 
     
     
         41 . The internal combustion engine in accordance with  claim 40 , wherein the flange of the cylinder liner forms the liner sealing face. 
     
     
         42 . An internal combustion engine in accordance with  claim 38 , with a cylinder-head seal that comprises a cylinder-head gasket comprising a metal sealing layer in which there are provided at least one combustion-chamber opening, screw holes each defining a screw hole axis around said opening for the passage of cylinder-head screws, and a combustion-chamber sealing bead stamped into the sealing layer, wherein the combustion-chamber sealing bead has, on its convex side, a crest portion which extends in the bead longitudinal direction and is arranged along the combustion-chamber sealing bead in a plan view of the sealing layer between two bead legs, by means of which bead legs the crest portion is connected to regions of the sealing layer bordering the combustion-chamber sealing bead, into which regions the bead legs transition in each case by a bead foot, and wherein in a plan view of the sealing layer the screw holes are arranged at a spacing from the combustion-chamber opening and at spacings from one another in the peripheral direction of the combustion-chamber opening and the combustion-chamber sealing bead runs between the combustion-chamber opening and the screw holes and has screw portions, each of which lies closest to a screw hole, and intermediate portions between these screw portions,
 wherein the deformation resistance of the bead legs with respect to pressing forces acting on the crest portion in the direction of the screw hole axes is greater at least in longitudinal regions of the intermediate portions of the combustion-chamber sealing bead than in screw portions of the combustion-chamber sealing bead.